1. Field of Invention
The present invention relates to a fabric picking and transferring device and method, for the transferring of one or more top fabric plies from a stack of such plies, and wherein the plies are engaged by at least two opposed picking needles inclined in offset facing relationship and at a shallow angle with respect to the plane of the uppermost ply. In addition, the device includes the combination of one or more separating needles which prevents fabric pieces under the engaged top fabric piece(s) from adhering to the engaged piece(s) when displaced from the stack.
2. Description of Prior Art
Various devices have been constructed in an attempt to transfer one or more top fabric pieces from stacks of fabric pieces and to position these engaged pieces at a remote station where another operation is effectuated. Presently known equipment has not been found satisfactory and the needletrade industry generally relies on manual labor to effect this operation. However, such operation is labor intensive, time consuming, and costly. There is therefore a need to provide an automatic separating and transporting machine wherein single fabric pieces or a few fabric pieces can be separated from the top of a stack of fabric plies without disturbing the underlying layers and transport it to a remote location to be superimposed in precise alignment at an unloading station, either for positioning the fabric pieces on other pieces, or else simply aligning them in position so that an operator can effect another function. Such machines should also be operated with minimum supervision, be precise, operate at high speed, and be capable of being synchronied with other machines in an assembly process.
Some of the devices known to attempt to effect this operation are disclosed in U.S. Pat. No. 3,981,495 and U.S. Pat. No. 4,613,123. These patents describe fabric carrying devices having sharp needle-like projections which move in opposite directions while the machine is pressing on the uppermost ply of a stack of plies whereby the needles engage and stretch the material to tighten and separate the engaged ply from the sub-plies. The disadvantage of such machines is the uncertainty of the separation process without disturbing underlying plies. Also, these machines can damage certain fabrics due to the stretching effected by the picking needles.
U.S. Pat. No. 3,176,979 and International Publication No. WO85/02389 published June 6, 1985 disclose devices to effect a fabric picking operation, but the disadvantage of these devices is that the stack of fabric plies must be perfectly straight and have an even surface in order for the picking mechanism to engage the fabric ply. These devices have not been found satisfactory to separate the engaged ply from the underlying plies without disturbing them. Another problem with these machines is that they cannot handle a stack of fabric plies having plies of various thickness or texture.
There are still other proposed methods for picking an uppermost fabric ply from a stack of plies, and some have suggested pinching and rolling the material through a predetermined space allowing only double of the material thickness to pass whereby the underlying ply would not adhere to the uppermost ply. Another disadvantage of this method is the limitation of picking a single ply only. Also the pinching of the material may leave undesirable marks or curls at the picking points at the edge of the material. Another disadvantage is that this method fails to handle tone-over-tone fabric, in other words, material of different thickness of texture at different locations along the material surface. Such machines require continuous adjustment when using different fabric materials and have been found to be limited to light and flexible materials only. They have not been found satisfactory to solve the problem of full separation without disturbing underlying plies.